Göbekli Tepe, is a hilltop sanctuary erected on the highest point of an elongated mountain ridge some 15 km northeast of the town of Şanlıurfa, in southeastern Turkey and 500 miles away from Istanbul, Turkey. It is the most astonishing archaeological discovery in modern times and also thought to be the oldest advanced civilization on Earth.Ancient Aliens Season - 02, Episode - 08 (Unexplained Structures).